joint bearing

joint bearing, also known as spherical sliding bearing, is composed of outer ring and inner ring. The outer ring has inner spherical surface and the inner ring has outer spherical surface. The sliding contact surface is treated by phosphating, frying, inlay, spraying, etc., and is equipped with lubrication holes and lubrication grooves [3-4]. It reduces lubrication dependence through composite material or PTFE fabric self-lubricating liner technology, has the characteristics of large load capacity, impact resistance, corrosion resistance, wear resistance, etc., and can realize multi-directional load and certain angle rotation. The bearing is suitable for low-speed swing and multi-directional movement, and can compensate for misalignment and bear deformation of peripheral components, widely used in construction machinery, automobile shock absorbers, water conservancy equipment, medical prostheses, surgical robots, humanoid robots and other fields, the classification covers centripetal, angular contact, thrust, rod end and other types, of which angular contact spherical sliding bearings can withstand radial and Axial combined load [. The project "Precision Transmission, Enabling Heavy Device-High-end Joint Bearing" won the championship in the 14th China Innovation and Entrepreneurship Competition Aviation Professional Competition [. Domestic enterprise Longxi shares independent research and development of PTFE fabric self-lubricating liner, products used in domestic large aircraft C919 and aerospace engineering.
The Chinese name is the nature of the joint bearing. The function of the sliding bearing bears a larger load. The structure is simpler than that of the rolling bearing.
Joint bearing
The structure of the joint bearing is simpler than that of the rolling bearing, which mainly consists of an inner ring with an outer spherical surface and an outer ring with an inner spherical surface. Joint bearings are generally used for low-speed swing motion (ie, angular motion). Because the sliding surface is spherical, it can also be tilted (ie, centering motion) within a certain angle range. When the degree is large, it can still work normally.
Features
The joint bearing can bear a large load. According to its different types and structures, it can bear radial load, axial load or radial and axial combined load. Due to the inner ring on the outer spherical surface of the composite material, so the bearing can produce self lubrication in the work. It is generally used for low-speed swing motion and low-speed rotation. It can also be tilted within a certain angle range. When the support shaft and the shaft shell hole are not concentric, it can still work normally. Self-lubricating joint bearings are used in water conservancy, professional machinery and other industries.
Application
Joint bearings are widely used in engineering hydraulic cylinders, forging machine tools, engineering machinery, automation equipment, automobile shock absorbers, water conservancy machinery and other industries. The joint bearing is a spherical sliding bearing, and the basic type is composed of an inner and outer ring with a spherical sliding spherical contact surface. Depending on its structure and type, it can bear radial load, axial load, or radial and axial combined load at the same time.
Self-lubricating joint bearing
Because the spherical sliding contact area of joint bearings is large and the inclination angle is large, and because most joint bearings adopt special process treatment methods, such as surface phosphating, galvanizing, chrome plating or outer sliding surface lining, inlay, spraying, etc., it has large load capacity and impact resistance, and has the characteristics of corrosion resistance, wear resistance, self-aligning, good lubrication or self-lubrication without lubricating dirt pollution, even if the installation is misplaced, it can work normally. Therefore, joint bearings are widely used for low-speed swing motion, tilt motion and rotation motion.
Composition
The joint bearing is mainly composed of an outer ring and an inner ring. The inner spherical surface of the outer ring and the outer spherical surface of the inner ring form a rolling friction pair.
Joint bearing performance: Because the structure and working mechanism of joint bearings are completely different from rolling bearings, joint bearings have their own technical characteristics and maintenance requirements.
Joint bearing
Working temperature
The allowable working temperature of the joint bearing is mainly determined by the matching material between the bearing sliding surface, especially the plastic material sliding surface of the self-lubricating joint bearing, and its carrying capacity will decline at high temperature. For example, when the sliding surface material of a lubricated joint bearing is paired with steel/steel, the allowable working temperature depends on the allowable working temperature of the lubricant. However, for all lubricated and self-lubricating joint bearings, they can be used in the temperature range of -30 ℃ ~ 80 ℃ and maintain the correct bearing capacity.
Inclination
The inclination angle of joint bearing is much larger than that of general adjustable center rolling bearing, which is very suitable for use in supporting parts with low concentricity requirement. The inclination angle of joint bearing varies with the size, type, sealing device and supporting form of bearing structure. Generally, the inclination angle range of radial joint bearing is 3~15 °, and the inclination angle range of angular contact joint bearing is 2~3 °, the inclination range of the thrust joint bearing is 6 ° ~ 9 °.
Cooperation
In any case, the joint bearing with the choice shall not make the ring uneven deformation, the choice of the nature and grade of the bearing must be based on the bearing type, support form and load size and other working conditions to determine.
Handling
The loading and unloading of joint bearings should follow the following principles, that is, the force applied by assembly and disassembly cannot be directly transmitted through the spherical sliding surface. In addition, the use of auxiliary loading and unloading tools, such as sleeves, remover, etc., the loading and unloading force exerted by the outside directly and evenly applied to the matching ferrule, or heating and other auxiliary methods for loading and unloading without load.
Joint bearing
Installation
When assembling joint bearing series, it is necessary to pay special attention to the position of the outer ring division surface. In order to avoid direct load on the split surface, it is necessary to maintain the split surface at right angles to the conforming direction.
Lubrication
When the applied load and the speed generated by the swing motion are very small, the oil-fed joint bearing can be operated without lubrication. Nevertheless, under normal circumstances must be regularly replenished grease. During the initial installation and operation, it is recommended that the lubrication cycle be appropriately shortened.
Oil-free joint bearings can be used without lubrication. However, if lithium soap-based grease is added before operation, the service life of the joint bearing will be extended. If grease is injected into the space around the bearing, the joint bearing will be more effective in protecting against the intrusion of dust and foreign bodies.
Classification features: radial joint bearing
(1)GE…E type: single seam outer ring, no lubricating oil groove. It can bear radial load and small axial load in either direction.
centripetal joint bearing
(2)GE…ES type: single seam outer ring, with lubricating oil groove. It can bear radial load and small axial load in either direction.
(3)GE…ES-2RS type, GEEW…ES-2RS type: single slit outer ring, with lubricating oil groove, with sealing ring on both sides. It can bear radial load and small axial load in either direction.
(4)GE…ESN type: single slit outer ring, GE…XSN type: double slit outer ring (split outer ring), with lubricating oil groove, outer ring with stop groove. It can bear radial load and small axial load in either direction. However, when the axial load is borne by the stop ring, its ability to bear the axial load is reduced.
(5)GE…HS type: the inner ring has lubricating oil groove, double half outer ring, the clearance can be adjusted after wear. It can bear radial load and small axial load in either direction.
(6)GE…DE1 type: the inner ring is hardened bearing steel, the outer ring is bearing steel. When the inner ring is assembled, it is extruded and formed with lubricating oil groove and oil hole. Bearings with an inner diameter of less than 15mm, without lubricating oil grooves and oil holes. It can bear radial load and small axial load in either direction.
(7)GE…DEM1 type: the inner ring is hardened bearing steel, the outer ring is bearing steel. When the inner ring is assembled, extrusion molding, bearing into the bearing seat, in the outer ring of the end groove to make the bearing axial fixed. It can bear radial load and small axial load in either direction.
(8)GE…DS type: The outer ring has an assembly groove and a lubrication groove. Only limited to large size bearings. It can bear radial load and small axial load in any direction (one side of the assembly groove cannot bear axial load).
angular contact joint bearing
GAC…S-shaped inner and outer rings are hardened bearing steel, and the outer ring has oil grooves and oil holes. It can bear radial load and axial (combined) load in one direction.
thrust joint bearing
GX…S type shaft ring and seat ring are hardened bearing steel; the seat ring has oil groove and oil hole. It can bear axial load or combined load in one direction (at this time, the radial load value shall not be greater than 0.5 times of the axial load value).
Rod end joint bearing
(1)SI…E type is an assembly of GE…E type bearing and rod end. Rod end with internal thread, the material is carbon structural steel, no lubricating oil groove. It can bear radial load and axial load less than or equal to 0.2 times radial load in any direction.
Rod end joint bearing
(2)SA…E type is an assembly of GE…E type bearing and rod end. The rod end is provided with external thread, and the material is carbon structural steel; without lubricating oil groove, it can bear radial load and axial load less than or equal to 0.2 times of radial load in any direction.
(3)SI…ES type is an assembly of GE…ES type bearing and rod end. Rod end with internal thread, the material is carbon structural steel; lubricating oil groove. It can bear radial load and axial load less than or equal to 0.2 times radial load in any direction.
(4)SA…ES type is an assembly of GE…ES type bearing and rod end. The rod end is provided with external thread, and the material is carbon structural steel; there is lubricating oil groove. It can bear radial load and axial load less than or equal to 0.2 times radial load in any direction.
(5)SIB…S-type rod end with internal thread, the material is carbon structural steel; the inner ring is hardened bearing steel; there is a lubricating oil groove. It can bear radial load and axial load less than or equal to 0.2 times radial load in any direction.
(6)SAB…S type rod end with external thread, the material is carbon structural steel; the inner ring is hardened bearing steel; there is lubricating oil groove. It can bear radial load and axial load less than or equal to 0.2 times radial load in any direction.
(7)SQ... type for the ball head rod end joint bearing, rod end for carbon structural steel; ball head for carburized steel. It can bear radial load and small axial load in either direction.
Self-lubricating centripetal joint bearing
(1)GE…C type and GE…T type: squeeze the outer ring, the sliding surface of the outer ring is sintered bronze composite material; the inner ring is hardened bearing steel, and the sliding surface is plated with hard chromium. Limited to small size bearings. The outer ring is bearing steel, and the sliding surface is a layer of PTFE fabric. The inner ring is hardened bearing steel, and the sliding surface is hard chrome plated. Can bear the direction of the same load, in the radial load at the same time, can bear any direction of the smaller axial load.
Self-lubricating centripetal joint bearing
(2)GE... CS-2Z type: the outer ring is bearing steel, and the sliding surface is sintered bronze composite material; the inner ring is hardened bearing steel, and the sliding surface is hard chrome-plated; both sides are equipped with dust covers. It can bear the load of the same direction, and can bear the smaller axial load in any direction while bearing the radial load.
(3)GEEW…T type: the outer ring is bearing steel, and the sliding surface is a layer of PTFE fabric; the inner ring is hardened bearing steel, and the sliding surface is plated with hard chromium. It can bear the load of the same direction, bear the radial load, and can bear the axial load in any direction.
(4)GE…F type: the outer ring is hardened bearing steel, the sliding surface is glass fiber reinforced plastic with polytetrafluoroethylene as additive, the inner ring is hardened bearing steel, and the sliding surface is plated with hard chromium. Can withstand the direction of the same medium radial load.
(5)GE…F2 type: the outer ring is glass fiber reinforced plastic, and the sliding surface is glass fiber reinforced plastic with polytetrafluoroethylene as additive; the inner ring is hardened bearing steel, and the sliding surface is hard chrome plated. Can withstand the direction of the same medium radial load.
(6)GE... FSA type outer ring is medium carbon steel, and the sliding surface is composed of glass fiber reinforced plastic discs with PTFE as additive, and is fixed on the outer ring with a retainer; the inner ring is hardened bearing steel. For large and oversized bearings. Can withstand large radial loads.
(7)GE…FIH type outer ring is hardened bearing steel; the inner ring is medium carbon steel, and the sliding surface is composed of glass fiber reinforced plastic discs with PTFE as additives, and is fixed on the inner ring with a retainer; Double half outer ring. For large and oversized bearings. Can withstand large radial loads.
Self-lubricating angular contact plain bearing
GAC…F type outer ring is hardened bearing steel; the sliding surface is glass fiber reinforced plastic with PTFE as additive; the inner ring is hardened bearing steel, and the sliding surface is hard chrome plated. Can withstand radial loads and axial (combined) loads in one direction.
Self-lubricating thrust plain bearing
GX…F type seat ring is hardened bearing steel, the sliding surface is glass fiber reinforced plastic with PTFE as additive, the shaft ring is hardened bearing steel, and the sliding surface is hard chrome plated. It can bear axial load or combined load in one direction (at this time, the radial load value shall not be greater than 0.5 times of the axial load value).
Self-lubricating rod end plain bearing
(1)SI…C type is an assembly of CE…C type bearing and rod end. Rod end with internal thread, the material is carbon structural steel. Can withstand the direction of the load. At the same time to bear radial load in any direction is less than or equal to 0.2 times the radial load of the axial load.
Self-lubricating rod end plain bearing
(2)SA…C type is an assembly of CE…C type bearing and rod end. Rod end with external thread, the material is carbon structural steel. Can withstand the direction of the load. At the same time to bear radial load in any direction is less than or equal to 0.2 times the radial load of the axial load.
(3)SI…CS-2Z type is an assembly of GE…CS-2Z type bearing and rod end. Rod end with internal thread, the material is carbon structural steel. At the same time to bear radial load in any direction is less than or equal to 0.2 times the radial load of the axial load.
(4)SA…CS-2Z type is an assembly of GE…CS-2Z type bearing and rod end. Rod end with external thread, the material is carbon structural steel. Can withstand the direction of the load. At the same time to bear radial load in any direction is less than or equal to 0.2 times the radial load of the axial load.
(5)SIB…C-type rod end with internal thread, the material is carbon structural steel, the sliding surface is sintered bronze composite material; the inner ring is hardened bearing steel, and the sliding surface is plated with hard chromium. Can withstand the direction of the radial load.
(6)SAB…C-type rod end with external thread, the material is carbon structural steel, the sliding surface is sintered bronze composite material; the inner ring is hardened bearing steel, and the sliding surface is plated with hard chromium. Can withstand the direction of the radial load.
(7)SIB…F-type rod end with internal thread, the material is carbon structural steel, the sliding surface is glass fiber reinforced plastic with polytetrafluoroethylene as additive; the inner ring is hardened bearing steel, and the sliding surface is hard chrome plated. Can withstand the direction of the radial load.
(8)SAB…F type rod end with external thread, the material is carbon structural steel, the sliding surface is glass fiber reinforced plastic with polytetrafluoroethylene as additive; the inner ring is hardened bearing steel sliding surface plated with hard chromium. Can withstand the direction of the radial load.
(9)SQ…L type is made of special self-lubricating alloy material, which can bear radial load and small axial load in either direction.
Calculation method: The joint bearing (spherical plain bearing) has two "fit" spherical contact surfaces, which is called coordinated contact. The calculation method of the mechanical properties of the joint bearing plays an important role in the structural design and wear analysis of the joint bearing. The calculation of the contact pressure of the coordinated surface is a very complex problem, and the existing Hertz model cannot be used to calculate the spherical coordinated contact pressure distribution because it is limited to the elastic half-space body. There is already a unified model of spherical contact, namely the Fang model, which can better solve the problem of contact pressure distribution of small deformation spherical contact, and this model is applicable to both non-coordinated contact and coordinated contact. However, the contact area of the joint bearing is not a complete sphere, and the calculation of its contact pressure distribution needs to be further calculated on the basis of the complete spherical coordinated contact model. In addition, the free boundary effect will also appear during the use of the joint bearing, which will have a certain impact on the application of the joint bearing. The free boundary effect produces contact pressure concentration and large pressure gradient at the outer ring edge of the joint bearing.